Is municipal composting logical for ag?

Municipal operations to turn kitchen scraps and garden waste into compost for large-scale farming would require the ultimate in recycling programs. Are we approaching that situation in the U.S.? A report out of New Zealand sees such recycling as feasible.

Research has been done in the Canterbury area of New Zealand where municipal composting schemes use around 50,000 tonnes of “green waste” to make 25,000 tonnes of compost each year.

“Plants need nitrogen and other nutrients to grow,” said Plant & Food Research organization scientist Abie Horrocks. “These nutrients and high levels of carbon are present in compost and adding it to soil boosts production. Because it can also supply the plants with nitrogen, a reduction in nitrogen fertilizer application is also possible without compromising yields.”

She went on to talk scale and economics. “Around 726,000 tonnes of garden and kitchen waste is buried in New Zealand landfills each year. The proximity of farms to the source of municipal compost will strongly influence the profitability of utilizing compost in agriculture. This research suggests that agricultural sectors close to populated areas, where municipal composting facilities could be developed, would benefit most from using compost and could result in redirecting most, if not all, green waste for profitable use.”

By adding compost and reducing nitrogen fertilizer by one-third the recommended rate, crops were show to yield 10 percent greater than standard practice field crops. Applying compost without reducing nitrogen fertilizer resulted in productivity increases of 14 percent over a three-year cropping rotation. When used in the production of forage crops, a yield increase of close to 50 percent was achieved compared to where no compost was applied.